Biden said he might leave race 'if I had some medical condition that emerged'

His latest in shifting reasons came before the White House said he had COVID-19.

"If there had [muffled] some medical condition that emerged, if somebody, if the doctors, came to me, said, 'you got this problem and that problem.' But I made a serious mistake in the whole debate, " he told BET's Ed Gordon n a preview clip of the interview set to air at 10 p.m. ET

The interview was done before the White House announced late Wednesday that Biden had tested positive for COVID-19, saying that his symptoms were mild.

Biden has now given several shifting reasons about what might make him decide to leave the race.

He told ABC News in a July 5 interview after his poor debate performance debate that only the "Lord Almighty" might get him to drop out.

In a news conference a week ago, he said he would stay in the race unless his aides told him he had no chance to win a second term.

"No, unless they came back and said, 'There’s no way you can win.' "No one is saying that. No poll says that," Biden told reporters.

Also in the BET interview, Biden said, "When I originally ran, I said I was gonna be a transitional candidate, and I thought that I'd be able to move from this just pass it on to someone else. But I didn't anticipate things getting so, so, so divided and quite frankly, and I think the only thing age brings a little bit of wisdom," he said. "And I think I've demonstrated that I know how to get things done for the country, in spite of the fact that we [were] told we couldn't get it done. But there's more to do, and I'm reluctant to walk away from that."

On Tuesday, he wholeheartedly endorsed Vice President Kamala Harris as not only a "great vice president" but so great that "she could be president of the United States," he said while addressing the NAACP national convention in Las Vegas.